Daily activity and behavioral thermoregulation of the guanaco (Lama guanicoe) in winter

Abstract

We investigated daily activity and the effects of ambient conditions on that activity to determine behavioral mechanisms of thermoregulation in the guanaco (Lama guanicoe). Observations of captive animals (an adult female, an adult male, and a yearling male) show that ambient conditions affect the posture of the animals. These behaviors have the effect of closing "thermal windows" in the axillary and flank regions, thus decreasing heat loss through radiation and convection. When the ambient temperature (Ta) was between 0 and 10°C, the animals used postural adjustments to decrease the area of the thermal windows to 5-7% of total surface area. At Ta > 10°C the animals increased the area (up to 22%) of the thermal windows to regulate heat loss through radiation and convection. When Ta was below 0-1°C the animals tended to bed and huddle together. Bedding and huddling were only initiated by the yearling. Another thermoregulatory behavior the animals exhibited was to bed with their hindquarters into the wind. Bedding and the orientation of the animal in the bedding posture are two behavioral strategies used to decrease convective heat loss. These postures can lead to calculated energy savings of 67%. Posture was determined to be one of the most sensitive parameters for regulating heat loss in the guanaco.